Water-soluble petroluem sulfonates



' c. E. WnLsoN 2,543,885

WATER-SOLUBLE PETROLEUM SULFONATES Filed Sept. 8, 1947 I Patented 6,1951 WATER-somma PE'rnoLUEM i sULFoNATEs chester E. Wilson, san Pedro,Cam., assignmto Union Oil Company of California, Los Angeles, Calif., acorporation of California.

Application September 8, 1947, Serial No. 772,783

9 claims. l

This invention relates to the production of sulfonic derivatives fromhydrocarbons and is particularly directed to the preparation ofwatersoluble petroleum hydrocarbon sulfonates which are highly activedetergents.

proved method of sulfonation of a selected hydrocarbon feedstock toobtain sulfonic acids and to amethod of fractionating these sulfonicacids so as to separate those which are highly detergent as alkali metalsalts and are both oiland watersoluble.

The preparation of organic sulfonic acids and of organic sulfonates foruse as detergents having many of the desirable properties of soap iswell known in the art. The sulfonic acids as such nd wide usage in thetextile, leather, paper, glue, petroleum and other industries. Thesulfonation product obtained from sulfonating a phenolsuch as esters ofcetyl, stearyl, and palmityl al cohols, which are related to sulfonicacids, are used as detergents.

Preparation of these sulfonic acids may be accomplished by contactingthe proper raw material with a sulfonating agent under proper conditionsfor the formation of the desired product. The variety of sulfonatingagents is quite large and includes sulfonating agents of widelydiffering activity from the stronger sulfonating agents such as oleum tothe milder sulfonation agents such as sulfur dioxide. These sulfonatingagents include concentrated sulfuric acid, oleum, sulfur trioxide, acidsulfates and polysulfates, chlorosulfonic acids, sulfur dioxide,sulfldes and acid sultes, hydrosuliides, N-pyridinium sulfonic acid,aminosulfonic acids, and the like. Generally, concentrated sulfuricacid, oleum, or chlorosulfonic acid are usually employed because oftheir high reactivity, low cost and ready availability. 'I'hesesulfonating agents are also nearly always l This invention furtherrelates to a method of producing a particular fraction of petroleumsulfonic acids by an imi" employed in the sulfonation of diicultlysulfonatable materials such as naphtha or parafn hydrocarbons of mineraloil fractions, etc.

The sulfonation of the'wide varietyofthe materials listed above in the'preparation of wetting -agents,..detergents, Vemulsfying agents,surfaceactive agents, etc. by using any one or a combination of thesulfonating agents also illustrated above is nearly always a complex andexpensive operation. The expense of preparing such detergents in generalarises from the requirement that the material being sulfonated must be arelatively pure material and the sulfonating agent employed is oftencostly. I have found that equally effective detergents, wetting agents,etc. may be prepared by the process of the present invention ashereinafter more fully described by using a particular mineral oilfraction, an inexpensive sulfonating agent, and fractionating thesulfonic acids formed so as to recover the most desirable types. Thesulfonation of a mineral oil fraction containing parain, naphthene,aromatic or condensed ring hydrocarbons found in such mineral oils forthe production of desirable petroleum sulfonic acids requires thestronger sulfonating agents. Concentrated sulfuric acid as the strongsulfonating agent is perhaps one of the least expensive of the reagentssuitable to perform the sulfonation according to this invention. Thesulfonation product thus obtained and particularly the salts formed fromthe sulfonation product have been found to be excellent emulsfying andwetting agents and perform at least as well as those prepared from themore expensive relatively pure raw material. It is to the improvement inthe method of production of petroleum sulfonates and to the productionof improved soluble petroleum sulfonates that this inventic is directed.

It is a primary object of this invention to provide an improved processfor the production of petroleum sulfonic acids and of petroleumsulfonates.

A further object of this invention is to provide a process for thesulfonation of selected mineral oil fractions and thereby produce aparticularly desirable fraction of petroleum sulfonic acids.

It is an additional object to provide a sulfonation process whereby aselected fraction of oiland water-soluble sulfonic acids may be producedfrom a selected hydrocarbon fraction with substantially no simultaneousformation of oilor water-insoluble sulfonic acids. f

A correlative object of this invention is to provide an economicalprocess for the production of surface-active agents from selectedhydrocarbon fractions.

Another object of this invention is to provide an oiland water-solublesulfonate prepared from selected petroleum hydrocarbon fractions, thepetroleum sulfonate being a highly active detergent.

Other objects and advantages of this invention will become apparent tothose skilled in the art as the description thereof proceeds.

Briefly, this invention comprises the sulfonation of a selectedhydrocarbon fraction with a concentrated sulfonating agent so as toproduce a particular fraction of hydrocarbon sulfonic acids which areboth oiland water-soluble and which form metal salts which are highlydetergent. The crude sulfonation product is subsequently quenched andextracted with a first organic solvent in order to cool the crudeproduct. thereby stopping the sulfonation reaction and to extract fromthe sulfonation product the particularly desirable fraction of sulfonicacids of this invention. This rst extract phase thus formed and whichcontains the oiland watersoluble sulfonic acids is thoroughly mixed witha solution of a basically reacting compound thereby forming thecorresponding salts of the sulfonic acids and forming simultaneously astable emulsion containing water, the first organic solvent, theunsulfonated hydrocarbon and the sulfonate salts. This emulsion issubsequently distilled to effect recovery of the ilrst organic solventwhich is reemployed in the process and the distillation residue istreated with a watersoluble alcohol to break the aforementionedemulsion. The distillation residue and alcohol is further extracted witha second organic solvent in order to effect separation of the sulfonatesalts from the unsulfonated hydrocarbon. 'I'he second organic solventdissolves the unsulfonated hydrocarbon and removes this material as asecond extract phase which is subsequently distilled to recover thesecond organic solvent. The rafnate phase which consists of an aqueoussolution of the sulfonate salts is subsequently de.- hydrated and thesulfonates recovered in substantially pure form as a very light coloredfree flowing powder.

The present invention may be more clearly understood and the sequence ofsteps in the process according to my invention may be more lucidlydescribed by reference to the accompanying drawing. This drawing is aschematic flow diai gram of the improved hydrocarbon sulfonation processand depicts and integrates the twelve esential steps thereof. l

Referring now more particularly to the drawing, the hydrocarbon feedintroduced into step I is thoroughly contacted under carefullycontrolled temperature conditions with a sulfonating agent alsointroduced into step I. The mixing of these two materials may be carriedout in any form of a reactor in which thorough contact of thesulfonating agent and the hydrocarbon feed may be effected and in whichsimultaneously the heat of reaction liberated may be removed quickly soas to maintain the desired temperature. I have found that theserequirements may be fulfilled by contacting the hydrocarbon feed withthe sulfonating agent in a horizontal cylindrical reactor which isprovided on the outside with a jacket and on the inside with ahorizontal rotatable shaft on the same horizontal axis as thecylindrical reactor. The horizontal shaft is provided with longitudinalblades aillxed thereto which continuously scrape the inside surface ofthe cylindrical reactor. The continuous scraping of the inside surfaceof the reactor by the blades attached to the rotating shaft assuresintimate mixing of the hydrocarbon feed with the sulfonating agent andsimultaneously assures good transfer of heat from the sulfonationreaction through the wall of the cylindrical reactor into a heattransfer medium circulated through the outer jacket. Proper selection ofthe heat transfer medium permits virtually any sulfonation temperatureto be maintained within quite narrow limits. Such a reactor as justdescribed and which is well suited to' the sulfonation process accordingto the present invention is commercially available and known to thetrade as a Votator manufactured by the Girdler Corporation ofLouisville, Kentucky, and is generally described in United StatesPatents Nos. 2,063,065 and 2,063,066, issued December 8, 1936.

The hydrocarbon feeds from which the soluble petroleum sulfonatesaccording to the present invention are prepared are selectednon-lubricating straight run non-cracked fractions of petroleumhydrocarbons, the major portion of which boils at temperatures greaterthan 500 F., such as between about 500 F. and 800 F. Petroleumdistillates prepared during the course of crude petroleum refining andwhich have a viscosity of less than about 110 SUS (Saybolt UniversalSeconds) at F. are suitable. Distillates in particular which haveviscosities ranging between about 40 and 110'SUS at 100 F. areapplicable. Preferably, distillates having viscosities of between 60 and100 SUS at 100 F. are used as the hydrocarbon feed employed in step l ofthe present sulfonation process.

Such distillates often include such materials as nitrogen bases,naphthenic acids, phenols, and

the like, constituents which lend no improvement to the desiredsulfonate product. The hydrocarbon feed may be pretreated to removethese extraneous materials by acid treating eliminating suchconstituents as nitrogen bases and olefinic materials, if present, whichincrease the sulfonation acid consumption. Naphthenic acids, phenols,and the like, may be removed by caustic washing, if desired.

Very often in petroleum refining, petroleum extracts are available suchas those produced in the sulfur dioxide or sulfur dioxide-benzenetreatment of petroleum distillates or other fractions according to thewell known Edeleanu process. These extracts contain a higherconcentration of aromatic type hydrocarbons and therefore contain ahigher percentage of sulfonatable materials. These particular petroleumfractions have been found to produce a desirable water-soluble sulfonateproduct when treated`accordlng to the improved process of the presentinvention. -Extracts suitable to the sulfonation process according tothis invention are desirably those having viscosities between about 50and 180 SUS at 100 F.

In addition to distillates and extracts which are both suitable ashydrocarbon feeds in the present process, selected intermediatefractions of hydrocarbons produced in refining operations may also beemployed. These intermediate fractions are exemplified by thosematerials which are produced during the repeated solvent extraction of ahydrocarbon stock or produced by the addition of a nonsolvent to anextract phase which serves to reject a portion of the extract. Othermethods are obviously available to produce such intermediate fractionsbut in general the desirable intermediate fractions include thoseconstituents which lie between the extremes of the insoluble and solubleconstituents present.

The sulfonating agent employed in step I to form the selected sulfonicacids from the preferred hydrocarbon distillates include the strongerand more active sulfonating agents. For certain hydrocarbon feeds theless active agents may be employed. In order to obtain an eiicient yieldof the desired sulfonic acids the best suited sulfonating agents includestrong sulphuric acid, oleum, sulfur trioxide, either in liquid or vaporphase, and chlorosulfonic acid. Of these, strong sulfuric acids having aconcentration greater than 80% and preferably a concentration of betweenabout 85% and 99% have been found to be the preferred sulfonating agentfor reasons of economy, sulfonation activity, and ready availability.

The quantity of sulfonating agent employed in step I in relation to thequantity of hydrocarbon feed to be sulfonated is an important factor inobtaining good yields of satisfactory sulfonic acids. I have found thatthe volumetric ratio of strong sulfuric acid to hydrocarbon feed should,in general, be less than 0.5 which corresponds to a ratio of one volumeof sulphuric acid for every two volumes of hydrocarbon feed. In thepreparation of sulfonic acids from selected petroleum distillates ashereinbefore defined, the volumetric acid to feed ratio preferablyranges between about 0.1 and 0.3. Such a volumetric ratio has been foundto result in they formation of very satisfactory sulfonic acids ansoluble sulfonates. In the preparation of sulfonic acids from theextracts or intermediate fractions previously describedv which contain asomewhat higher concentration of sulfonatable constituents the desirableratio of volumes of acid to volumes of feed is between about 0.2 and0.5, and may under certain circumstances run as high as 0.8. v

Another important consideration in obtaining satisfactory oilandwater-soluble sulfonates from the selected hydrocarbon distillates isthe temperature and duration of the sulfonation reaction. The preferredconditions of time and temperature in the preparation of sulfonatedproducts from the preferred hydrocarbon distillates in the sulfonationreactor previously described is a residence time of about three minutesand an outlet crude sulfonation product temperature of about 200 F.Although these are the preferred conditions a somewhat modified productmay be obtained by employing residence times as high as about fifteenminutes when the crude sulfonating product is removed from the reactorat a temperature of as low as about F. Residence times of less thanthree minutes, for example, as low as about one-half minute are feasiblewhen outlet temperatures as high as about 300 F. are employed. Withdistillates which are readily sulfonatable, residence times of less thanone minute may be employed at temperatures above about 250 E. Theoptimum conditions of three minutes residence time and 200 F. outlettemperature was arrived at for consideration of the rate ofdecomposition of sulfonic acids at temperatures above 200 F. and the lowrate of sulfonic acid production at low temperatures with high residencetimes. It is therefore desirable to maintain the lowest possibleresidence time by operating at the highest possible sulfonationtemperature sulfuric acid.

without excessive degradation of the desired sulfonic acids.

The crude sulfonation product comprising unsulfonated hydrocarbon feed,sulfonic acids formed in step I, and sulfuric acid sludge is removedfrom step I and introduced into step 2, as indicated on the accompanyingdrawing. In step 2 the crude sulfonation product is extracted with anaromatic organic solvent indicated on the drawing as Solvent A. Theextraction step 2 may be conveniently carried out in a vertical columnpacked Berl saddles, Raschig rings, or other packing in which an eicientextraction of the crude sulfonation product by means of Solvent A isaccomplished. This extraction may also be carried out in a series ofmixing vessels by introducing the crude sulfonate product into Solvent Ahalts the sulfonation reaction at a desired point and minimizes theamount of sulfonic acid degradation.. Solvent A also serves tofracgtionate the desirable Water-soluble and oil-solu'- ,ble sulfonicacids from the crude-sulfonation product and effects a rejection of thedarker colored undesirable acids tothe sludge and retains the lightercolored oiland water-soluble sulfonic Yacids in the extract phase. Theoperations of step 2 may also be performed by mixing Solvent A with thesulfonation product followed by a centrifuging operation to separate thesludge. The extract or Solvent A phase produced in step 2 comprises asolvent solution of unsuifonated hydrocarbon feed together with thedesirable sulfonic acids and a small amount of The railinate or sludgephase comprises the sulfuric acid sludge which is subsequently treatedas hereinafter more fully described prior to disposal.

The quantity of Solvent A introduced into step 2 to accomplish thepreviously described operations varies with the type of hydrocarbon feedbeing sulfonated. In sulfonation of the preferred type of hydrocarbonfeed, that is, selected hydrocarbon distillates, the ratio of the volumeof Solvent A introduced into step 2 to the volume of hydrocarbon feedintroduced into step I is about 1.0. However, depending upon the type ofdistillate employed the Solvent A to hydrocarbon feed `ratio may varybetween about 0.5 and 3.0. When the hydrocarbon feed being sulfonatedcomprises extracts which contain an increased concentration ofsulfonatable constituents the quantity of Solvent A employed is somewhatgreater. The ratio of the volumes of Solvent A to the volume of thehydrocarbon feed in the latter case is generally about 2.0, but may Varyfrom about 1.0 to 4.0 or more, depending upon the characteristics of theparticular extract. It is preferred that the temperature of Solvent A below, for example, at

tion. In other cases where the ratio of solvent to feed is higher thesolvent need not be cooled but may be introduced at temperatures ofabout 100 F. or higher. However, a solvent at the ambient temperature orabout 80 F. is preferred.

Particular solvents which fulll the requirements of Solvent Ahereinabove disclosed include such aromatic solvents as benzene and itshomologs such as toluene, ethyl benzene, xylene, and aromatichydrocarbons containing less than about ten carbon atoms per molecule,chlorinated benzenes and chlorinated homologs of benzenes such aschlorobenzene and chlorotoluene, etc., together with the normally liquidchlorinated aliphatic hydrocarbons such as carbon tetrachloride,dichloroethylene, etc. Of these particular solvents the preferredsolvent in general comprises benZene. As Solvent A, therefore, purebenzene as prepared from petroleum or from coal tar distillates, oraromatic concentrates, extracts prepared from aromatic gasoline andtherefore containing benzene homologs besides benzene, and the like, arelikewise applicable.

'I'he extract phase produced in step 2 and, with the preferred SolventA, comprising a benzene solution of sulfonic acids and unsulfonatedhydrocarbon feed is introduced into step 3. Within step 3 the benzenesolution is thoroughly mixed with an aqueous solution or slurry of abasically reacting agent forming an emulsion of sulfonate salt, solvent,water and unsulfonated hydrocarbon. It is preferred that this aqueoussolution be introduced at a temperature of about 120 F., a1- thoughtemperatures as low as room temperature to temperatures higher than 120F. are applicable. Elevated temperatures, however, are to be avoided inorder to minimize sulfonic acid decomposition. Although sulfonates maybe prepared by using amines and other nitrogen bases as the basicallyreacting agent, the preferred neutralizing agent is a basically reactingcompound of an alkali metal such as the bicarbonate, the carbonate orthe hydroxide of sodium, potassium, or lithium. Because of itsavailability sodium hydroxide is the preferred alkali metal compoundemployed to neutralize the sulfonic acids in step 3, although obviouslyother basically reacting alkali metal compounds may be employeddepending upon the particular alkali metal desired in the finishedwaterand oilsoluble sulfonate. 'I'he concentration of this neutralizingsolution is preferably between about 5% and 15% by Weight in water, theproper concentration being determined by the quantity of waterintroduced into the system. For subsequent steps a certain amount ofwater is desirable and it is well to introduce the required amount ofwater in step 3. The petroleum sulfonic acids, being quite strong acids,are somewhat corrosive and are apt to be contaminated by dissolved ironresulting from corrosion of the materials of construction employed inthe equipment used in the first-two steps. The iron contaminationresults in the formation of a dark colored sulfonate salt product whichis undesirable.

The quantity'of sodium hydroxide introduced into step 3 to form thesoluble sulfonates according to this invention is, therefore, preferablysomewhat in excess of the theoretical quantity required to convert thesulfonic acids and sulfuric acid present to their sodium salts, forminga slightly alkaline emulsion and thus precipitate the iron as insolublehydroxides. A slight excess of sodium hydroxide such as from about 1% toas high as about may be employed in step 3 to neutralize the sulfonicacids and also causes the precipitation of iron hydroxide which maysubsequently be separated. The resulting liquids have a pH somewhatgreater than 7.0 thereby substantially eliminating acidic corrosion oi'equipment. Excesses of sodium hydroxide to give a pH of about 7,0 to10.0 have been found desirable.

The neutralized material formed in step 3 and consisting of water,benzene, unsulfonated hydrocarbon feed, sodium sulfonate and a smallamount of excess sodium hydroxide is in the form of a first emulsion andis transferred from step 3 to step 4 wherein this emulsion is heated anddistilled to eiIect the recovery of the Solvent A or benzene. Because ofthe presence of water in the emulsion the benzene is removed overheadtogether with water and the operation is in essence a steamdistillation. In step 4 better than of the benzene is recoverable bydistillation and is ultimately returned and used as Solvent A in theextraction of the crude sulfonation product in step 2. Benzene and othersolvents which may be employed as Solvent A are quite soluble in theaqueous sodium sulfonate part of the emulsion and therefore adistillation as carried out in step 4 is necessary to effect asubstantially complete benzene or Solvent A recovery.

The sludge produced from step 2 contains a small amount of Solvent Atogether with a certain amount of the desirable soluble petroleumsulfonic acids. For this reason, the sludge is introduced into step 5and is extracted by means of Solvent A recovered from step 4. An extractphase is produced consisting largely of Solvent A and containssubstantially all of the desirable sulfonic acids present in the sludge.A railinate phase is also produced consisting of the sludge and a smallamount of Solvent A. The extraction in step 5 may be carried out in acountercurrent continuous manner in a packed extraction column or in aseries of mixing vessels as previously indicated in connection with thedescription of step 2. The extract phase produced in step 5 is returnedand introduced into step 2 together with fresh Solvent A.

The rafinate, or sludge phase, produced in step 5 is introduced intostep 6 wherein a distillation of the sludge is effected preferably underconditions wherein the sludge acid is not appreciably diluted, therebyavoiding excessive corrosion of dilute acid. Such a distillation ispreferably carried out under reduced pressure whereby the quantities ofSolvent A remaining with the sludge extracted in step 5 are removed. TheSolvent A present usually amounts to between 5% and 10% of the totalquantity used and may be combined with the extract phase from step 5 forreturn to step 2 for reuse. The extracted and distilled sludge isremoved from step 6 and discarded or sent to storage.

The distillation bottoms produced in step 4 and consisting of an aqueoussolution of rsodium sulfonate and the unsulfonated hydrocarbon feedassociated together as a second emulsion is mixed with an alcohol tobreak the emulsion and is introduced into step I for further treatmentas hereinafter more fully described. The alcohol is preferably a lowboiling water-soluble aliphatic alcohol having less than four carbonatoms per molecule. It has been found that isopropanol is well suitedfor use at this point in the process, although ethanol and methanol arealso applicable and may be used if desired.

The quantity of alcohol introduced may vary between considerable limits,however, it has been found than an ideal composition of the materialintroduced into step 1 contains about flve gallons of isopropanol(anhydrous) for every 100 pounds of sodium sulfonate together with about25 gallons of water, which mixture usually also contains of the order of20 pounds of solubilized unsulfonated hydrocarbon feed. The isopropanolmust not necessarily be added in its anhydrous form so long as thecomposition given above is approximated. These compositions usuallyexist as two phases, an aqueous phase containing predominantly water,alcohol, sodium sulfonate and sodium sulfate, and an oil phasecontaining predominantly unsulfonated hydrocarbon. Sometimes whensomewhat larger amounts of sodium sulfate are formed, three phasesresult which include a water and sodium sulfate phase, analcohol-water-sodium sulfonate phase, and an unsulfonated hydrocarbonphase.

The aqueous and oil phases are introduced together into step 1 whereinthey are extracted by a Solvent B in an extraction tower or other meansindicated as applicable in previous extraction steps. The function ofSolvent B in step 1 is to separate unsulfonated hydrocarbon feed fromthe material introduced from step l. Certain requisites of Solvent Bmust be closely adhered to in order to obtain satisfactory petroleumsulfonate product. Solvent B should be free from odoriferousconstituents such as some organic compounds of nitrogen and sulfur whichhave been found to impart undesirable odors to the product. Solvent B isrequired to have a high solvent power for the type of hydrocarbon whichis unsulfonated in step I. I have found that a paralnic naphtha boilingin the lower gasoline range, such as from about 100 F. to 300 F. andcontaining parain hydrocarbons having between about 4 and carbon atomsper molecule is suitable for use as Solvent B in the step 1 extractionand that a suilicient separation of the unsulfonated hydrocarbon feed isobtainable. A petroleum naphtha such as that just described is thepreferred form of Solvent B although other materials of the same generalcharacter may be employed. If available, pure pentanes or hexanes may beemployed as Solvent B and even paraffin hydrocarbons having as few asthree carbon atoms per molecule may be employed as Solvent B byconducting the extraction in step 1 under a suitable elevated pressure.The use of low molecular weight paraffin hydrocarbons such as propanehas been found to be advantageous because of the ease of removal of thesolvent from the extract and traces of solvent from the raillnateproduced in such an extraction.

It is possible to produce a sulfonate product which contains as low asabout 0.5% by weight of unsulfonated hydrocarbon feed by employing a lowboiling naphtha rich in hexanes as Solvent B, and using an'extractioncolumn which contains the equivalent of about five equilibrium stages.Temperatures between about 140 F. and 200 F. are preferred for thisextraction operation, however, temperatures as low as about 60 F. may beemployed, particularly when propane is used as a solvent.

The extract phase produced from step 1 and comprising a naphtha solutionof the unsulfonated hydrocarbon feed is introduced into step B whereinthe extract phase is distilled. An overhead product of Solvent B isobtained and returned to step 1 as previously described. 'I'hedistillation bottoms produced in step g coml0 prises the unsulfonatedhydrocarbon feed substantially free of Solvent B.

The raffinate phase produced from the step 1 extraction and comprising awater solution of sodium sulfonate and a small amount of sodium sulfatetogether with alcohol and a small amount of Solvent B is introduced intostep 9 and distilled at a temperature of around 200 F. to recover asubstantial amount of the alcohol and remove substantially all of theSolvent B present. The distillation in step 9 may be carried out bysimple heating, or with the aid of steam and/or vacuum to facilitate theremoval of the alcohol and Solvent B at as low a temperature as ispossible. avoid overheating of the sodium sulfonate product although thesulfonates are not as thermally sensitive as the parent sulfonic acids.The overhead product obtained in the distillation of step 9 may beretreated to separate the alcohol and Solvent B. The distillationbottoms from step 9 comprising a concentrated aqueous solution of thesodium sulfonate product is introduced into step III for clarification.

It is highly desirable that soluble petroleum sulfonates besubstantially free of suspended solids or color bodies such as ironhydroxides and it is to this end that an excess of sodium hydroxide orother basically reacting neutralizing agent is employed in step 3. Instep I0 the aqueous sodium sulfonate solution may be treated in a1centrifuge or in settling basins to permit the removal therefrom of anysolid materials. Iron hydroxide introduced through corrosion is removedfrom the alkaline solution in this manner. Step I0 may also comprise anadsorbent treatment whereby color bodies are adsorbed from the solutionif present. It is sometimes feasible to employ a filter in step I0 forclarifying the sodium sulfonate solution. Under proper control asubstantially clear aqueous solution of sodium sulfonate product isproduced from step I0.

It is often desirable to increase the quantity of sodium sulfate presentover the amount which normally is present in the product as previouslydescribed. The sodium sulfate may be introduced into the aqueoussulfonate solution immediately before dehydration step I2 in which thesolid product is obtained. When this is done quite concentrated sodiumsulfate solutions may be added. In another method, the sodium sulfatemay be added to the aqueous raffinate prior to clarification step I0, inwhich case any impurities may be removed from the sodium sulfonate.

The aqueous solution of sodium sulfonate produced in step I0 isintroduced into step II wherein a required amount (of dilute acid isadded in order to neutralize the remaining eX- cess of sodium hydroxideor other neutralizing agent present. The dilute acid employed ispreferably sulfuric acid since a certain amount of sodium sulfateinvariably arises in step 3 by neutralization of the small quantity ofsulfuric acid present in the extract phase produced from step 2 aspreviously mentioned.

The aqueous sodium sulfonate product solution discharged from step Ilhaving a pH of about 7 is introduced into step I2 wherein the solutionis dehydrated for the production of the sodium sulfonate product as agranular solid. The apparatus involved in step I2 may comprise anevaporator followed by a spray drier, or may comprise an evaporatorfollowed by It is desirable to' "#evaporators wherein sodium sulfonatemay bef.'

separated in substantially pure form from the sodium sulfate which ispresent. The apparav tus may consist of low pressure evaporator feedi-nga highly concentrated solution of sodium sulfonate into a drum or vacuumtray drier, or "the like. A considerable quantity of steam is 4producedfrom step l2 together with the alco- 'hol which was not recovered duringthe distillation of step 9, and it is desirable that the alcoholcontaining vapor thus produced be returned to the process. This materialmay be employed in making up the aqueous neutralization solution or fedto an alcohol recovery unit which may conceivably follow step 9. Thesolid peytroleum sulonate product produced according to the process justdescribed in general contains between 75% to 85% by Weight of awatersoluble sodium sulfonate and between about and by weight of sodiumsulfate. The 1 latter percentage may be increased by adding sodiumsulfate to the solution introduced into step I0. If in step l2 a spraydrier is employed i, the product is a nearly white free-flowing finelydivided powder which is highly soluble in water i* and mineral oils andin solutions of brine. In

ence to the following example:

Example I The hydrocarbon feed employed in a specific sulfonationoperation according to this invention comprised a spray oil distillateboiling in the range of from about 500 F. to about 800 F. and having thefollowing properties:

Gravity, 22.0 A. P. I.

Viscosity at 100 F., 85.6 S. U. S. Viscosity at 210 F.. 36.5 S. U. S.Acid solubility, 36% by volume Flash point, 295 F.

Fire point, 320 F.

Pour point, F.

Color, 4% N. P. A.

The sulfonation of 65 gallons or about 500 pounds of spray oildistillate having the above-described properties was carried out with182 pounds of 98% sulfuric acid as the sulfonating agent. Thesulfonation reaction was conducted in a Votator, with hot water passingthrough the jacket of the sulfonation reactor. A residence time of threeminutes and a crude sulfonation product outlet temperature of 200 F. wasemployed in this operation.

The crude sulfonation product obtained from the Votator was mixed with65 gallons of benzene Y at 80 F., an amount which corresponded to aspray oil distillate-benzene ratio of 1.0. Over the period of the run 65gallons of benzene were added. The crude mixture resulting wascentrifuged and the benzene-extract phase and the rafllnate sludge phaseseparated.

The benzene-extract phase. containing the desirable sulfonic acidsaccording to this invention,

was neutralized at about 120 F. with an aqueous solution comprising 22pounds of sodium hyg caustic soda.

' droxide in 25 gallons of water which is equivalent to 230 pounds of a9.6 weight per cent solution of The neutralization was carried out 12with thorough agitation and the resulting emulsion distilled to effectrecovery of 58.5 gallons of benzene which was reused in the process.

The sludge-raffinate phase formed by centrifuging the mixture of benzeneand crude sulfonate product was extracted with 581/2 gallons of benzenerecovered, as just described, so as to recover from the sludge railinatea small quantity of desirable sulfonic acids which would otherwise bediscarded therewith. The extracted sludge was subjected to a vacuumstripping operation at about five pounds per square inch absolutepressure and 3.3 gallons of benzene recovered. Makeup benzene in theamount of 3.2 gallons was added so that a total of fresh benzene,benzene recovered from vacuum stripping of the acid sludge and benzeneextract obtained from the sludge-ralnate extraction amounted to 65gallons. This quantity of material was recirculated and employed in thebenzene extraction of the crude sulfonation product produced from theVotator. The acid sludge. substantially free of benzene and the desiredtype of sulfonic acids, was discarded.

The residue remaining following recovery of benzene from the emulsionformed comprised a very stable emulsion of Water, unsulfonatedhydrocarbon feed, the sodium soaps of the sulfonic acids, and the smallamount of benzene. Five gallons of isopropyl alcohol were added in waterto break this emulsion into an aqueous phase and an oil phase. These twophases were subsequently extracted with 50 gallons of a petroleumnaphtha boiling between about 170 F. and 220 F.

' This naphtha extraction was carried out in a packed extraction columnat a temperature of about 170 F. About 95 gallons of extract wasobtained which consisted predominantly of the naphtha solvent and theunsulfonated hydrocarbon feed. Due to the wide differences in boilingpoint of these two materials, the extract was distilled in a columnhaving less than ve theoretical trays to effect the recovery of 45gallons of naphtha, which was re-employed in the process, from 49gallons of unsulfonated hydrocarbon feed.

'I'he raffinate obtained from the naphtha extraction comprised anaqueous solution of sodium sulfonates, isopropyl alcohol, together withsmall amounts of solubilized naphtha and unsulfonated hydrocarbon feed.This material was distilled at a temperature of about 220 F. and about2.5 gallons of alcohol and about 2.5 gallons of naphtha were recovered.No additional sodium sulfate was added to the aqueous distillation bot-ltoms which were subsequently passed through a centrifuge and a smallquantity of solids consisting namely of ferrie hydroxide removed fromthe solution. The clear liquid obtained following centrifuging of thedistillation bottoms had a pH of about 9 due to a small excess of sodiumhydroxide purposely employed in the neutralization of the sulfonic acidspresent in the benzene extract. The pH of this aqueous sodium sulfonatesolution was adjusted by the addition of dilute sulfuric acid so thatthe resulting solution had a pH of '7.0.

The neutral aqueous solution of sodium sulfonates thus obtainedcontained pounds of sodium sulfonates in about 25 gallons of water. Inorder to obtain the sodium sulfonate as a dry powder the neutralsolution was introduced at room temperature through an atomizer into aspray drier. The drier employed flue gases introduced at a temperatureof 600 F. as the source 13 of heat. The flue gases were generated byburning natural gas at a constant rate and the drier outlet gastemperature was maintained at a value of 230 F. by varying the rate ofintroduction of the aqueous sulfonate solution into the drier. Thesegases containing the sodium sulfonate as asuspended powder was removedfrom the drier and passed through a series of cyclone separators forrecovery of the sodium sulfonate product.

The dry sodium sulfonate product was a nearly white colored free-flowingfinely granulated material having virtually no odor. It was found to besoluble in water and to form a foam of high stability. The dry sodiumsulfonate was also found to be soluble in benzene, methanol, and inmineral oils such as the spray oil distillate from which it wasprepared. This material was further found to be substantially insolublein acetone and Baum sodium-chloride brine solutions. This dry powderedsulfonate product having the above solubility characteristics was shownto contain 19% sodium sulfate and 81% sodium sulfonates, which lattercomprised the active ingredient.

The above example is intended merely to illustrate the preferredmodification of the process of preparing the sulfonic acid andsulfonates of the present invention. The above example is not intendedto describe limitations of the present invention but rather to moreclearly dene the scope thereof. Although strong sulfuric acid isemployed as the sulfonation agent other of the stronger sulfonate agentssuch as sulfur trioxide, chlorsulfonic acid, sulfonylchloride, and thelike, may be substituted without departing from the scope of the presentinvention. The preferred sulfonation stock has been described ascomprising a hydrocarbon distillate having particular properties cfviscosity, however, the extracts prepared from such distillates or otherfractions of such distillates may be treated according to the methodsherein defined. High molecular weight alcohols, vegetable oils such ascastor oil, etc. may be sulfonated according to the method of thepresent invention in order to obtain sulfonates of somewhat differentcharacters than the product obtained from petroleum distillates. l

This product, prepared according to the foregoing example, has manydistinct advantages over sulfonates prepared by different methods.First, it contains an extremely high concentration of the active sodiumsulfonate ingredients thereby permitting the employment of a smalleramount of material for a given application. Second, the sodiumsulfonates, according to this invention, are prepared from inexpensiveraw materials and not from highly purified and manufactured chemicalsallowing a low cost of production. Third, the product is produced by acontinuous process using inexpensive and readily available solvents andreagents. Fourth, the product obtained is soluble in both oil and waterforming solutions having high detergent powers, and is also soluble indilute brines and hard waters.

This sulfonate product has been found to be at least equal ineffectiveness to more expensive sulfonate type detergents prepared fromalkylated aromatic type hydrocarbons or from high molecular weightalcohols. This is believed to be at least partly due to the substantialabsence in the sulfonate product of by-products of side reactions of thesulfonation reaction.

The foregoing description and examples are not to be taken as in any waylimiting but merely 'illustrative of my invention for many variationsmay be made by those skilled in the art without departing from thespirit or scope of the following claims:

I claim:

1. A process for the production of watersoluble hydrocarbon sulfonateswhich comprises reacting a hydrocarbon oil fraction boilingsubstantially between 500 F. and 800 F. with a strong sulfonating agentat an elevated temperature to produce a crude sulfonation product.

extracting said crude sulfonation product with a first solventconsisting essentially of at least one organic solvent selected from theclass consisting of liquid aromatic hydrocarbons having 6 to 9 carbonatoms per molecule, monochlorinated liquid aromatic hydrocarbons having6 to 9 carbon atoms per molecule and polychlorinated aliphatichydrocarbons having l to 2 carbon atoms per molecule to form a firstextract phase and a. sludge phase, separating said first extract phasefrom said sludge phase, neutralizing the sulfonic acids in said firstextract phase with an aqueous solution of a basically reacting alkalimetal compound to form a first mixture, separating said rst solvent fromsaid rst mixture leaving a second mixture, extracting said secondmixture with a second solvent consisting essentially of at least oneliquid aliphatic hydrocarbon having between about 3 and 10 carbon atomsto form a second extract phase and an aqueous phase, separating thesecond extract phase from the aqueous phase, and recovering saidsulfonate salts from the aqueous phase.

2. A process according to claim l in which the hydrocarbon oil is apetroleum distillate having a viscosity between about 40 and 110 SayboltUniversal Seconds at 100 F., the sulfonating agent is sulfuric acidhaving a concentration greater than about 80% by weight, the ratio ofsulfonating agent to hydrocarbon oil employed in the sulfonationreaction is between about 0.1 and 0.5, and the sulfonation reaction iscarried out at a temperature between about 50 and 300 F. for a timebetween about 0.5 minutes and l5 minutes.

3. A process according to claim 1 in which the hydrocarbon oil is anaromatic extract from the selective solvent treatment of a petroleumdistillate and has a viscosity between about 50 and 180 SayboltUniversal Seconds at 100 F., the sulfonating agent is sulfuric acidvhaving a concentration greater than about 80% by Weight, the ratio ofsulfonating agent to hydrocarbon oil is between about 0.2 and 0.8, andthe sulfonation reaction is carried out at a temperature between about50 and 300 F. for a time between about 0.5 and l5 minutes.

4. A process for the production of watersoluble hydrocarbon sulfonateswhich comprises reacting a hydrocarbon oil fraction boilingsubstantially between about 500 F. and 800 F. with between about 0.1 and0.8 volumes of sulfuric acid having a concentration greater than aboutby weight at a temperature'between about 50 and 300 F. and a timebetween about 0.5 and l5 minutes to produce a crude sulfonation product,extracting said crude sulfonation product with a rst solvent consistingessentially of at least one organic solvent selected from the class Yconsisting of liquid aromatic hydrocarbons having 6 to 9 carbon atoms per molecule, monochlorinated liquid aromatic hydrocarbons having 6 to 9carbon atoms per molecule and polychlorinated aliphatic hydrocarbonshaving 1 to 2 carbon atoms per molecule to form a first extract phaseand a sludge phase, separating said rst extract phase from said sludgephase, neutralizing the sulfonic acids in said ilrst extract phase withan aqueous solution of a basically reacting alkali metal compound toform a first mixture, distilling said first solvent and a portion of theWater from said iirst mixture, leaving a second mixture, adding to saidsecond mixture a water-soluble aliphatic alcohol containing less than 4carbon atoms, extracting the resulting mixture with a second solventconsisting essentially of at least one liquid aliphatic hydrocarbonhaving between about 3 and 10 carbon atoms to form a second extractphase and an aqueous phase comprising an aqueous solution of saidalcohol and said water-soluble hydrocarbon sulfonate salts, separatingsaid phases, and recovering said sulfonate' salts from the aqueousphase.

5. A process according to claim 4 in which the first solvent is anaromatic hydrocarbon having less than 10 carbon atoms.

6. A process according to claim 4 in which the basically reacting alkalimetal compound is sodium hydroxide.

7. A process according to claim 4 in which after the second extractphase is separated from the aqueous phase, the aqueous phase isdistilled to separate therefrom any residual second solvent, thealcohol, and part of the water, and the residual aqueous solution ofwater-soluble hydrocarbon sulfonates is clarified by separatingundissolved solid material therefrom, before recovering the sulfonates.

8. A process according to claim 4 in which an excess of sodium hydroxideis employed as the basically reacting alkali metal compound forneutralization, the second extract is separated from the aqueous phase,the aqueous phase is distilled to recover the alcohol therefrom, and theremaining aqueous solution 'is clarified by removal of undissolvedsolids therefrom and neutralized before recovering the sulfonates.

9. A process for the production of watersoluble petroleum sulfonateswhich comprises reacting a petroleum distillate boiling substantially inthe range of about 500 F. to 800 F. and having a viscosity betweenabout40 and 110 Saybolt Universal Seconds at 100 F. with about 0.1

16 to 0.5 volumes of sulfuric acid having a concentration between aboutand 99% by Weight for a time of about 3 minutes at a temperature ofabout 200 F. to produce a crude sulfonation product, extracting saidcrude sulfonation product with an approximately equal volume of a firstsolvent consisting essentially of an aromatic hvdrocarbon having lessthan 10 carbon atoms Lc form a rst extract phase, and a sludge phase,separating said first extract phase from said sludge phase, neutralizingthe sulfonic acids in said rst extract phase with an excess of anaqueous solution of sodium hydroxide to form a rst mixture comprisingsaid first solvent, water, unsulfonated oil, and water-soluble sodiumsulfonates, distilling said first mixture to separate therefrom saidfirst solvent and a portion of the water, adding sufiicient isopropylalcohol and water to the residue to form a second mixture comprisingwater, sodium sulfonates, isopropyl alcohol, and unsulfonated oil in theproportions of about 5 gallons of isopropyl alcohol for every pounds ofsodium sulfonates and every 25 gallons of water. extracting said secondmixture with a second solvent consisting essentially of a paraftinicnaphtha boiling between about 100 F. and 300 F. to form a second extractphase and an aqueous phase containing said aqueous solution of alcoholand sulfonates, separating the second extract phase from the aqueousphase, distilling the aqueous phase to recover said alcohol. separatingundissolved solids from the remaining aqueous phase, neutralizing theresulting aqueous phase with sulfuric acid, and dehydrating the productto form a mixture of sodium sulfonates and sodium sulfate.

CHESTER E. WILSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,358,773 Blumer Sept. 26, 19442,368,452 Dawson Jan. 30, 1945 2,381,708 Amott et al Aug. 7, 19452,395,774 Amott et al Feb. 26, 1946 2,396,673 Blumer Mar. 19, 19462,406,763 Grieslnger Sept. 3, 1946

1. A PROCESS FOR THE PRODUCTION OF WATERSOLUBLE HYDROCARBON SULFONATESWHICH COMPRISES REACTING A HYDROCARBON OIL FRACTION BOILINGSUBSTANTIALLY BETWEEN 500* F. AND 800* F. WITH A STRONG SULFONATINGAGENT AT AN ELEVATED TEMPERATURE TO PRODUCE A CRUDE SULFONATION PRODUCTEXTRACTING SAID CRUDE SULFONATION PRODUCT, FIRST SOLVENT CONSISTINGESSENTIALLY OF AT LEAST ONE ORGANIC SOLVENT SELECTED FROM THE CLASSCONSISTING OF LIQUID AROMATIC HYDROCARBONS HAVING 6 TO 9 CARBON ATOMSPER MOLECULE, MONOCHLORINATED LIQUID AROMATIC HYDROCARBON HAVING 6 TO 9CARBON ATOMES PER MOLERCULE, MONOCHLORINATED ALIPHATIC HYDROCARBONSHAVING 1 TO 2 CARBON ATOMS PER MOLECULE TO FORM A FIRST EXTRACT PHASEAND A SLUDGE PHASE, SEPARATING SAID FIRST EXTRACT PHASE FROM SAID SLUDGEPHASE, NEUTRALIZING THE SULFONIC ACIDS IN SAID FIRST EXTRACT PHASE WITHAN AQUEOUS SOLUTION OF A BASICALLY REACTING ALKALI METAL COMPOUND TOFORM A FIRST MIXTURE, SEPARATING SAID FIRST SOLVENT FROM SAID FIRSTMIXTURE LEAVING A SECOND MIXTURE, EXTRACTING SAID SECOND MIXTURE WITH ASECOND SOLVENT CONSISTING ESSENTIALLY OF AT LEAST ONE LIQUID ALIPHTICHYDROCARBON HAVING BETWEEN ABOUT 3 AND 10 CARBON ATOMS TO FORM A SECONDEXTRACT PHASE AND AN AQUEOUS PHASE, SEPARATING THE SECOND EXTRACT PHASEFROM THE AQUEOUS PHASE, AND RECOVERING SAID SULFONATE THE AQUEOUS PHASE,AND RECOVERING SAID SULFONATE SALTS FROM THE AQUEOUS PHASE.